The present invention relates to water pipes using more than a single stage of water to condition smoke before it reaches the user's mouth.
U.S. Pat. No. 4,357,948 shows a water pipe with a device located in a tube above a bottom water reservoir. The device can only form large and non-uniform bubbles from smoke filled air passing through water retained in the device. The device loses almost all effectiveness when tilting it more than a few degrees from vertical, as a relatively low water head at one side of the tube allows all the smoke filled air to escape through the water at the point where the depth is smallest.